Knock-On Effect
by TheSilverHunt3r
Summary: They were making their last stand against Fyodor. Chuuya cursed, he needed to hurry. Chuuya centric, time travel, one shot.


Summary: They were making their last stand against Fyodor. Chuuya cursed, he needed to hurry. Chuuya centric, time travel, one shot.

1\. Shattering into pieces

"Cold waters, too shallow

To keep me from the fire

The harder I swallow

The more it's paralyzes

Is this how it ends?

Is this how it ends?"

\--Glass Heart, Tommee Profitt

Yokohama

Chuuya's office

Age 27

Mori propped his chin on his hand. "Both of you were promising candidates for becoming the Boss. And I knew there wouldn't be fighting between you about who got it, you would figure out some way." He trained his gaze on his executive. "Tell me, why did I push Dazai out of the Port Mafia?"

Chuuya calmly took another sip of wine, a considering look in his eyes. "Why did you kill the old boss? What's the one thing that allowed us to work with our natural enemies?" He rhetorically questioned. "Yokohama is our city, and we want to stop it from being hurt, from being turned into a pile of rubble and bones." He shrugged, "But Dazai lacked that aspect for years." His face was only slightly red-he wasn't drunk, only a bit inebriated.

Mori hummed. "And now?"

"He cares for more people and, by extension, the city they love." Chuuya smirked wryly. "Not that it matters much to the Port Mafia since we can't get him to come back."

Mori laughed. "True. Now, what about yourself?"

"Myself?" Chuuya questioned, confusion on his face.

"Yes. You care," Mori stated.

Chuuya raised an eyebrow. His face was wary. He stayed silent-he wasn't stupid.

"I'm going to leave the Port Mafia," Mori abruptly said.

Chuuya's eyes went wide. "...What?"

Mori shrugged, absently swirling the wine in his glass. "I wanted to congratulate you on becoming boss before I left."

Chuuya blinked owlishly. He frowned. "Thank you," he quietly replied.

XXX

Mori died in a car crash the next morning.

That afternoon, Fukuzawa retired and handed over the reins of the Armed Detective Agency to Kunikida.

The two new heads of Yokohama's greatest ability organizations stepped up on the same day. Chuuya Nakahara, the Port Mafia's one man army, and Doppo Kunikida, the level headed, driven idealist.

XXX

Yokohama

Chuuya's new office

The room had been remodeled. It was brighter, more lively-the silver chandeliers cast a soft light throughout. He had added some cabinets along a part of the wall, one of them was just to hold the wine from his old office.

"Akutagawa." The smoke Chuuya exhaled floated around him, forming a thin haze.

"Yes, Boss?" Akutagawa stood stiffly in front of the polished wooden desk. He relaxed as Chuuya smiled, a small genuine smile, the type that had grown rarer since he had resolved to spend most of his time at his desk instead of out in the field.

"Congratulations on your promotion," Chuuya said, a hint of teasing in his voice. He pushed a piece of paper forward, towards Akutagawa.

Akutagawa looked down, reading the piece of paper. "What?" He choked out, shock and joy mixing together, making it hard for him to breathe.

Chuuya snorted quietly. "You're now an executive. Congratulations."

XXX

The meeting between Chuuya and Kunikida was tense.

Then… Dazai said, "That rafter would be great-it's just high enough for me."

"Dazai, stop," the two leaders said in unison. They looked at each other in surprise. Smiles grew on their faces, and they shook hands. And there was their solidarity, their immediately agreed upon common ground-Dazai was annoying and often acted like an idiot. They had both been partnered to him, and both could empathize with the pain they had suffered on a daily basis.

"My condolences for having to deal with him," Chuuya said, completely serious.

"The thought is much appreciated." Kunikida rubbed the bridge of his nose.

It was the start of an odd but beautiful friendship.

XXX

Yokohama

A small cafe near the sea

Mori knew he would be found by him.

There was no way Dazai wouldn't come; he was far too curious. Somehow still far too confident in his own intelligence. Somehow still far too trusting that Mori wouldn't do anything to him.

Mori had reverted to what he had looked like before he became the Boss. Although his face was a bit more thin, it was the same white doctor's coat, the same rough stubble on his chin, and the same sharp violet eyes.

Dazai looked completely the opposite from what he had been before. He had exchanged black clothes for tan. His eyes were less dead. His smile was still just as fake, looking sugary sweet, but truly, it was composed of salt instead.

Mori smiled pleasantly at his protege. "Hello, Dazai-kun."

XXX

Everything was fine for a while, a long while. Yokohama settled down. The Port Mafia and the Armed Detective Agency had a tense, yet strong alliance. They stayed out of each other's way.

That's how everyone should have known everything would go terribly, horribly wrong.

XXX

Yokohama

Chuuya's office

Age 31

Chuuya didn't know how, but Dazai had broken into one of the most secure buildings in the world. Of course, this was sort of par for the course with his old partner.

Dazai was sitting in the large chair behind the desk, feet propped up, spine curved from slouching, body completely relaxed. "Fyodor is back," were his words that heralded the end of the peace in Yokohama. "I don't know if my plan will work. Actually, I'm pretty sure it will fail and we'll all die," Dazai cheerfully relayed.

Chuuya sighed. He put the folders in his hands on the desk corner, as far away from Dazai's reach as possible. "What's the best way to stop Dostoyevsky from getting his hands on the Book?"

"Kill him?" Dazai joked, pointing out the obvious solution.

"Or, change the situation...?" A look of realization settled on Chuuya's face. "I'm going to go find someone, an ability user. Figure out how to cover for me not being here."

"An ability user? Where?" Dazai questioned, his curiosity piqued.

"England."

Dazai raised his eyebrows in doubt. "You're going to the Order of the Clock Tower for help?"

Chuuya snorted. "No, I'm not stupid, thanks. I'm going to track down a defector of theirs. I ran into him a few years ago."

"A defector who stuck around in England?" Dazai smirked. "He must be pretty cocky."

XXX

England

Last time they had seen each other, they somewhat got along? But Chuuya also had to jump out of a window to avoid Wells near the end. The story of what happened when Chuuya went to Britain involved multiple arsons, the murder of two thieves, a smoke grenade, and six apricots. Unfortunately, we do not have time to tell that story.

H. G. Wells had fled into the country. Chuuya followed the trail with the help of some English contacts. He found Wells's house, an old vine covered cottage outside of Newquay.

Chuuya's phone buzzed. He pulled it out. It was a simple text.

Mackerel: X

They were making their last stand against Fyodor. Chuuya cursed-he needed to hurry.

He knocked on the door. As soon as he caught sight of his target, he demanded, "Wells, I need to use your time machine."

"Chuuya Nakahara," Wells testily replied. "Why?" He was dressed in a suit. He had a clean shaven face and short black hair.

The images Chuuya imagined of what was happening back home were almost worse than being there and knowing for sure how they were dying. He pitched the one idea that would work-the truth. "I'm trying to stop the plans of Fyodor Dostoyevsky."

At the name, Wells straightened up. "Fyodor Dostoyevsky? You're trying to screw over that b*stard?"

Chuuya nodded. His knuckles were white under his gloves, fists clenched at his sides. "Yeah. He's about to get pretty close to ruling the world," he replied, tersely.

Wells smiled. "Well then, I guess there's nothing else to do but help, even with only one trip left in 'er." He closed the door behind himself and stepped outside onto the grass. "Put a bullet in him for me, ehh mate?"

2\. Glue and Duck Tape

"Do you know when the right time to chicken out and go home is? There is no such time."

\--Chuuya, Dead Apple

Traveling through time with H.G. Wells's machine had seven rules:

H.G. Wells cannot use the time machine himself, but he is the one person who can turn it on.*

The time machine can be used three times to travel back into the past, and only three times.

The time traveler can only use the time machine once.

The time traveler can only go backwards in time exactly ten years.

If a time traveler uses the machine, he or she will commandeer his or her former self's body.

The machine will not stay with the time traveler.

XXX

Yokohama

Chuuya's apartment

Physical age 21

Mental age 31

Chuuya woke up in his old apartment. It had been destroyed by a bombing a few years back. . . Or a few years from now?

He stretched out his arms for a moment before getting up. He changed into his work clothes. His 21-year-old self had far less scars than his 31-year old-self. Not to say that his skin didn't have it's fair share of burns, knicks, bullet scars, and knife wounds already, but there were definitely less.

Chuuya drove to work. All the while he put himself into the mindset of his past self.

He had a game plan to start with. He would act like his old self until he got into a battle. Then, he would give himself a concussion. *

XXX

Yokohama

Mori's office

Mori noticed the change in Chuuya's personality. He frowned and looked for an explanation.

He glanced at Chuuya's medical records. Chuuya had gotten injured. How unusual. Chuuya had gotten a concussion a few days ago. That would explain things.

Mori sighed and put his elbows on his desk. He should check on Chuuya's concussion himself and give his subordinate some time to get better. He was a doctor, after all, and one of the best, albeit one that had lost his license to malpractice and became a criminal. He would be remiss as both a doctor and a boss if he ignored his subordinates' ailments and got someone killed for no reason.

XXX

Yokohama

Chuuya's apartment

Chuuya had to wait before doing anything out of the ordinary. But he could plan things out.

Now to the problem.

Chuuya had no delusions about things. How the f*ck was he going to take care of people that included Dazai's genius tactician rival, Fyodor Dostoyevsky?

Dostoyevsky. He was the immediate problem. After him, Chuuya could worry about people like Agatha Christie...

But first was how to derail Dostoyevsky's plans. Chuuya could just do something different and throw a wrench in the b*stards' plans.

That was too simple.

What was Dostoevsky after this whole time? Taking out competition and control of Yokohama… all for the Book. The Book was his goal.

How could Chuuya hide the Book? There were hints scattered around… some hidden, others found and kept by different groups, from the Special Abilities Department to the Port Mafia.

Well, the Port Mafia one would be easy. But what about the others?

XXX

Yokohama

Unknown house

There were four geniuses that lived in Yokohama. Dazai, Mori, Ranpo, and Ayatsuji. Dazai had already left and was at the Agency. Mori would be suspicious. Chuuya didn't want his Boss's attention focused on him; he wanted to have his Boss's full trust to operate without anyone taking note of him. Ranpo was part of the Agency and wouldn't trust him. He also had no reason to not backstab Chuuya and take the Book. Finally, there was Ayatsuji, a brilliant detective, and someone who possessed a moral code… of sorts. Someone that Chuuya could somewhat call a friend and someone who, despite being an asset of the Special Abilities Department, wouldn't sell Chuuya out.

The security team on the roof changed people, and during that minute of distraction and chatter, Chuuya slipped inside.

"I assume there's an important reason as to why you're here, Chuuya?" Ayatsuji blew out a puff of smoke. His boots were on the top of his desk. The detective was in his usual outfit, minus his coat.

"I'm here to enlist your help." Chuuya dropped into one of the room's comfortable chairs and draped his coat over one of its arms.

"To do what?" Ayatsuji shifted his arm to a more comfortable position.

"I'm from the future. I need to kill some people before they get the Book."

Ayatsuji scrutinized his friend for several minutes. "Have you changed anything yet?"

"Not anything significant." Chuuya shrugged. "Things start heating up about ten months from now."

Ayatsuji nodded slightly, considering. He was silent for a minute. He hummed, a slight smirk on his face as he questioned, "So who are the people you need to kill?"

"A few very-hard-to-kill, genius-level b*stards."

"You seem rather annoyed." Ayatsuji chuckled. "What did they do?"

"When I was leaving, Yokohama was being turned into ruins," Chuuya deadpanned.

"Ah," Ayatsuji muttered. "What for?"

"Ever heard of the Book? It's an object in Yokohama that can alter reality. This bunch of megalomaniacs all want it."

"So kill them before they have a chance to get their hands on it?" Ayatsuji surmised.

"Not exactly. I have about a year until things really start, a year until the Guild show up, and a year and a half-ish until Fyodor." Chuuya leaned forward, propping his elbows on his knees and chin on his hands. "I need you to help me find all of the clues and destroy them."

Ayatsuji raised an eyebrow. "You trust me with knowing all of the hints to the location of the Book? You know I'll be able to figure out where it is."

"You hate people who play with too many other people. You don't like out-of-control nutjobs getting too much power." Chuuya smirked. "You're my best option out of Yokohama's geniuses."

This was the best solution Chuuya could come up with. At the least it would hinder everyone who was trying to find the Book.

XXX

Yokohama

Chuuya's apartment

The end of Yokohama had turned his unpleasant but tolerable dreams into the occasional nightmare that didn't let him sleep until morning came.

Chuuya staggered to his sink. He tried to push past the frayed remnants of his nightmare. He couldn't. The pile of flesh and bodies scattered among the war-torn streets of Yokohama were too vivid. The faces of his colleagues-former and current, torn and mangled limbs, the bloody pulp of mashed muscle with bits of bone...

He shivered. His brain seemed to enjoy tormenting him with new, creative ideas of how they died. Mori, Kouyou, Dazai, Hirotsu, Akutagawa, Gin, Tachihara...

But now, right now, they were all alive.

His grip on the sink tightened.

He would not witness their deaths. He would not let them die.

XXX

He got some sleep medication suggestions from Mori the next day. It didn't make things less terrifying-they just let him stay asleep while he faced down his night terrors.

3\. Kintsuji

"The world breaks everyone and afterward many are strong at the broken places."

\--Ernest Hemingway

Yokohama

Port Mafia dungeons

Physical age 22

Mental age 32

Chuuya had figured out how to handle Dazai, as sometimes he just wasn't up for squabbling. It took a bit of trying, but eventually he could ignore Dazai's teasing and mocking with a poker face. Plus… Chuuya could always hit Dazai later as payback for trying to distract him.

Dazai had been captured by the Port Mafia, just like in the first timeline.

Chuuya walked down the steps. Unlike the first time, they were calm, firm paces, no extra flair. "What are you here for? The weretiger, right?" He asked, eyebrow raised.

"Did your small brain get slightly bigger in the past few years?" Dazai teased.

The red eyebrow was just raised higher. He kept silent, an unspoken mocking back of Dazai's attempt to provoke him. He moved on. "I heard about the letter already. So let's just get this over with. Akutagawa is in charge, and the files are on the second floor, last door on the right." He turned around.

Dazai didn't like this. He didn't like it at all. His plan for killing time and a fun reunion were out the window. "Oh? Aren't you going to unchain me?" He wondered in a high voice.

"Well, I can't do all of the work for you," Chuuya dryly shot back.

Dazai's predictions were never wrong. His predictions were never wrong. His predictions were never wrong. Dazai repeated the mantra as Chuuya's footsteps slowly faded down the corridor.

Dazai lowered his chin, eyes dark.

His predictions were wrong.

XXX

Yokohama

Chuuya's apartment

Chuuya needed a new game plan. He had been making this up as he went. But he really needed to figure things out before things started to heat up.

How could he stop Fyodor? Keep him from getting the Book.

Right, but they'd already found all of the hints...

Chuuya facepalmed.

They had all of the hints in Yokohama already.

Chuuya could get the Book. He could destroy it or hide it somewhere else. But he couldn't do it now. There were too many eyes, too much paranoia about the Port Mafia's movements.

He would wait.

XXX

Yokohama

A forest outside the city

Rescuing Q went the same-until Dazai changed his response.

"You're such a hypocrite," Chuuya scoffed.

"It's called growing, Chibi." Dazai looked over his shoulder, a thoughtful mocking look on his face. "But I guess you wouldn't know that."

It was a two-fold insult-literal and metaphorical, Dazai's regular type of joke about Chuuya's height and an insinuation against his character. Chuuya couldn't stop the glare he directed at Dazai for the comment. He clicked his tongue in annoyance. Dazai had been sticking mostly to script up till now, but he had caught Chuuya completely off guard with that jab. He shook his head. "I still can't believe you're going with a good Samaritan act," he groused. He wondered how long Dazai would keep it up this time.

Dazai laughed as he picked up Q, satisfied. It was still Chuuya, still the same glare, still the same hat, still the same monstrous strength. They both had changed some, but they were still Double Black. The heavy weight, the paranoid unease, in Dazai's stomach settled.

XXX

Yokohama

Alleyway, near the Armed Detective Agency's office

Physical age 23

Mental age 33

Chuuya did the expected thing and got caught in Poe's book with Ranpo. It was what needed to happen.

But...

He hated this place. He hated this place. He hated this place with a searing rage.

When Dazai nullified his ability, it was like being underwater for a short period of time-he would be fine. All he had to do was hold his breath and wait it out.

But here in Poe's book, it was suffocating. It felt like there was no oxygen anywhere. It was the type of thing that people who lived at the bottom of a valley would experience if they were suddenly teleported to the top of Mount Everest with snow gear. The air was too thin and there wasn't enough of it- every breath felt like inhaling ice.

The void in his chest was there again-the comfortable weight in his chest that came from using his ability was gone. Fear and hate at his discomfort filled the void, giving him a spike of adrenaline and paranoia.

He pulled off his gloves, knuckles white as he clenched them into fists.

'Where was Ranpo?' His thoughts, the logical side of his brain, reminded him. There was a reason he had fallen into this trap. While they were in here, there was no way for anyone to know what was happening. Dostoyevsky wouldn't be able to know about it.

"Oi, Ranpo," Chuuya called out.

The detective halted in his tracks. He turned around. "Yeah, Mr. Fancy Hat?"

Chuuya unclenched his fists. He locked eyes with Ranpo. Chuuya's eyes were oceans-drowning in them was easy if you were unaware. In this light, one could see the inky black and blue bottom of the ocean.

The sight gave Ranpo an uneasy feeling that there were monsters lurking out in the dark, just beyond his field of vision.

"This is for," Chuuya paused, mulling over his word choices, "...upcoming events, so I need you to give this message to Dazai: Keep Dostoyevsky occupied fully while you're in there."

XXX

Fyodor and Dazai had both been arrested and imprisoned. With Fyodor and Dazai playing their citywide game of metaphorical chess, nobody was paying attention to the Port Mafia.

This left Chuuya with a window of a day or so to find the Book.

XXX

Yokohama

Unknown house

Ayatsuji was reading a book, but the door to his office had opened. It was strange-it wasn't Tsujimura, no chatter or footsteps. Ayatsuji looked up-Chuuya was in his armchair. He took off his reading glasses and raised an eyebrow at his friend. "Taking full advantage of the lack of security around me?"

"I'm looking for a treasure map or a compiled list of hints, if you'd make one for me." Chuuya gave a knowing look. "I know you copied all of them down again after you destroyed them."

"A treasure map for the Book?" Ayatsuji smirked and closed his book. He pulled out a folder of various papers and a map of Yokohama. "I haven't put them all together, but I have them, minus the one in the Port Mafia's hand that went missing two years ago." He raised a meaningful eyebrow at Chuuya. "But of course, you'd have no idea where that would be."

Chuuya smiled innocently as he pulled out a scrap of yellowed paper. "Laying on the sarcasm a bit thick there."

Together, they went over the clues for several hours. They were incredibly cryptic, often riddles or poems with double meanings and some sort of trick to figuring them out.

Ayatsuji glanced over the last two notes, putting them side by side. He pulled the buried map out from under the pieces of paper. He marked a spot with an x. "You asked for a treasure map," Ayatsuji reminded with a smirk.

Chuuya snorted.

XXX

Yokohama

Exact location unknown

Chuuya inspected the abandoned shack near the river. The ground was marshy, mud and long climbing plants squelched under his feet.

He counted paces from the three trees around the shack, marking where he stopped with a stick. He drew lines from those sticks, connecting them together. He dug where they intersected.

Buried beneath the earth was rusty metal box with a lock.

Chuuya didn't have a key. It was probably lost sometime in the past few decades. He resorted to a more crude method, bending the arc of metal open.

Inside the waterproof box was a book. It was bound in what looked to be a modern style, but with an unmarked title and no author listed anywhere. Its pages were a pristine white, even though they should have been yellowed with age. A few of the snowy pages had been carefully torn out, only leaving a small visible space in the spine where they should be.

He tried tearing it apart, lighting it on fire, and various other methods of destruction.

Nothing worked.

He clicked his tongue and wracked his brains.

And there was an idea. He smiled and withdrew a pen from his pocket.

He chose a page and wrote:

No being can change reality using this book or any page out of it anymore.

The words of change rippled out into the world. The words crossed countries and oceans, sinking into the earth and air. The fabric of reality shifted to account for the wish.

The ripples from the wish came back, bearing the punishment, the whiplash, the karma for using the Book.

Chuuya hissed.

He felt something burn on the left side of his chest, a feeling reminiscent of a hot poker being held against his skin. He hurriedly unbuttoned his shirt, wincing at the pain.

The words he had written were now on his skin, in the same black calligraphic swirls of his own hand. They proceeded vertically down his ribcage in neat rows of kanji.

"F*ck," he swore. He ran a hand through his hair, agitated.

He checked. The Book was now a regular book.

He burned it.

There had been a problem with his wish. The Book was gone, the fabric of reality safe from Fyodor's hands getting on it. But changing reality with words, the job had to be done by something or someone. . . So it had passed it on to him.

He felt like there was something tied to his right hand, a thread. He felt like he could hear things, things that weren't there. He thought he could remember things, things that had never happened. He felt like he could see other things, things that weren't there.

Well, things that weren't there in that reality, that universe, that doomed timeline he had changed. Chuuya had made an entirely new set of universes. He knew that now.

The extra information was already giving him a headache. He was definitely taking off work for a few days.

XXX

Yokohama

Chuuya's apartment

Chuuya wrapped a roll of bandages around his ribcage, tight enough they wouldn't fall, loose enough he could breathe. He was taking a page out of Dazai's book, but it felt better to have an extra layer over the scar.

He figured out how to dim the extra sense he now had, the one that shrieked about other things and other people in other worlds. He just had to ignore it, stuff the sensation inside, not tug on the string.

It would have probably been harder for someone who was human. But Chuuya wasn't and never had been. He was the incarnation of Arahabaki. He had learned how to control his unnatural side years ago, how to turn the rage and the wish to burn everything down to the ground into overflowing calm.

The Book's powers were different than the ones that came from being Arahabaki, but weren't too difficult to get a handle on. It was a lot easier to not stare into an abyss, than to be the abyss and hold yourself back from swallowing everything that approached.

XXX

Yokohama

Unknown house

"I'm going to admit it," Chuuya dryly said. "I f*cked up."

Ayatsuji's eyebrows knitted together in concern. "Did you lose the Book?"

"No, that's not the problem. I found the Book. I used it, making it useless. And like an idiot, I was too wrapped up in stopping Dostoyevsky and didn't even think about the Book's karma."

"What happened?"

"I'm… now the Book," Chuuya confessed.

Ayatsuji stared at Chuuya for a moment. He sighed, massaging the bridge of his nose. "I didn't see that one coming either."

"I have it under control," Chuuya notified. "My problem is how to play things now."

Ayatsuji stared at his friend. He had one problem. "You could have just lied to me about what happened. Why are you telling me this?"

"You've kind of been my partner in crime for getting the Book," Chuuya pointed out. He dismissed the notion with a wave of his hand. "Besides, you'd have figured it out eventually, so it's better to get it out of the way."

XXX

Yokohama

A cafe near the sea

Dazai got out of prison. He went to talk to Mori about how to deal with Dostoyevsky in the future. Dostoyevsky would be back, sometime soon-the idea of a reality-changing item was too much of a lure for him to ignore.

They met at the outside patio of an idyllic cafe near the sea.

Mori ordered tiramisu and coffee. He had been up all night filing paperwork for the Port Mafia's front businesses. Being a Mafia Boss was not fun, however much the movies made it seem dangerous and exciting, there were far more dry and dull moments.

Dazai settled with a bubble tea and small plate of mochi. He had an arm lazily propped on the table.

They discussed plans and counterplans, weak points that could be exploited, and the location of the Book. The salty breeze washed around them, soaking into their clothes and skin.

The legs of a chair scraped the stone floor as it was put down at their table.

"Chuuya/Chuuya-kun," the two tacticians said in surprise.

Chuuya put his arms on the table, leaning forward slightly. "I thought there was something the two of you needed to know." He paused, meeting their eyes, making sure he had their full attention; and with those cryptic words and sudden arrival, he did. "I'm not the me you knew. I am a… me from the future. I destroyed the Book so no one could get their hands on it."

Mori thoughtfully looked at Chuuya. He hadn't been blind to the improvements in strategy or the slowly developing insomnia of his executive over the past two years. "You did well," was all he said.

Dazai tilted his head, resting his cheek on his fist. "Ranpo noticed that you didn't seem that shocked about being in Poe's book." He grinned, a look of realization in his eyes. "So you're an old man? It all makes sense! I told you your hat would eat your brains if you kept wearing it."

Chuuya shook his head. "I can't wait until you actually get some sense again. Not that you ever get much, but it's better than now," he groused.

Dazai pouted sullenly at his insult being ignored and took a bite of his mochi.

Mori took a sip of his coffee, using the cup to block his unsuppressable, amused smile at their antics.

XXX

Yokohama

Rooftop, exact location unknown

Chuuya sat on the edge. He had never feared heights. He let a leg dangle lazily over the street.

The rooftop was warm, lit softly by the slowly disappearing sun at the edge of Yokohama. Streetlights were already on, providing an artificial whitish-yellow glow to the streets below.

The packet of Golden Bat cigarettes was almost empty-only two were left. Chuuya shifted the container, snagging one for himself. He turned his head slightly. "Want one?" He offered.

Dazai walked out onto the rooftop. His steps were light and confident. "Sure." He shrugged his shoulders.

Chuuya lobbed the cigarette over his shoulder. A lighter followed soon after-Dazai never had one on him; even when he bought one, he forgot it somewhere.

Dazai caught them in his right hand with a lazy sort of ease. He could still somewhat predict Chuuya's movements. It helped that the habits of throwing things at him hadn't changed a bit. He lit the cigarette, perching on the edge of the rooftop near Chuuya. "That was not the full truth. You're keeping something, a very important ace up your sleeve." He tilted his head, studying Chuuya's reaction. "It's so important, that you can't tell us."

Chuuya smiled bitterly. "Yeah, it's that important."

Dazai sighed. "Okay." He gave a dramatic look of disappointment and resignation. "I guess I'll just have to settle for making up theories," he lamented.

Chuuya snorted.

XXX

Yokohama

Exact location unknown

Physical age 24

Mental age 34

The building had fallen in such a way that it created a small shelter. Dazai and Chuuya had decided to hide, after Dazai had miscalculated the enemy's strength and was almost skewered. He would have been, if Chuuya hadn't shoved him out of the way.

Chuuya gritted his teeth. "This is bad."

"Yes, that is rather obvious." Dazai was wrapping bandages around his left shoulder. Blood had already trickled out from the graze, staining the sleeve of his tan coat.

Chuuya stared at the ceiling for a few seconds, his gaze unfocused. He clicked his tongue in annoyance. If they failed here… everything would fall to pieces again. He tossed his knife over to Dazai. "Get over here," he snapped.

"Chibi?" Dazai questioned as he caught the knife, but he did as requested.

Chuuya unbuttoned his vest and shirt, draping them over his arm. He started unraveling the bandages around his chest. He pointed with a finger to the right side of his rib cage. "I need you to carve the best solution into my skin," he calmly explained. With a grimace and piercing look aimed at Dazai he tacked on, "And please don't be long winded or ask for the death of someone. I can direct the karma to something that's not too serious if someone doesn't die from your wish."

Dazai was silent as he crouched slightly to unwind the bandages around his partner's ribcage. His mind was buzzing with too many thoughts.

The sight of the words on Chuuya's left side in a familiar script-Chuuya's own handwriting-burned itself into Dazai's brain, wrecking through the other theories like a truck at 150 mph. The pieces of the puzzles slotted together. Chuuya hadn't destroyed the Book, not really-he hadn't been able to.

"Chuuya," Dazai breathed out, genuinely shocked for once in his life. There had never been a universe in which Chuuya was the Book, never-until now. And he didn't like it, he didn't like it at all.

"Dazai, shut up and write," Chuuya ordered with a scowl, "Unless you really want everyone to die."

Dazai tried to do it as shallow as possible. He used the tip of Chuuya's knife, going slowly. He kept his breathing calm and steady, eyes laser focused to the bleeding, scratchy handwriting he was leaving on his old partner's skin.

Having words carved into your skin was painful, even if the person wielding the knife was experienced and careful. Chuuya bit down on his lip to keep himself from reacting. After a few words, his lip started bleeding.

The wait was agonizing for both of them. Seconds drew into hours, shouts and gunfire rang for millennia.

Dazai removed the knife from Chuuya's skin and stepped away.

Chuuya sat down and leaned against the slanted wall. He withdrew into unconsciousness to deal with the rebound of Dazai's wish.

Dazai wiped off the tip of Chuuya's blade. He rewrapped Chuuya's bandages around his chest, spots of red now on the right side. He buttoned up Chuuya's shirt and vest. He was gentle, not wanting to brush against the fresh wound.

The battle had resolved, and everyone else had fled with injuries.

Dazai picked Chuuya up carefully. He would have dropped Chuuya's hat on the floor if not for his instincts, shifting the weight of the unconscious body backward slightly to snag the rim on his fingers. He put it back on Chuuya's head, where it belonged.

He hummed as he hauled himself and Chuuya out of the empty battlefield. That reveal was interesting and unexpected… but things were a lot better now. He had the Book on his side and made a wish.

Now, where to drop Chuuya off, his apartment? He didn't have a key. Dazai grinned. When had that stopped him from dropping by before?

XXX

Yokohama

Agency office

The office of the Armed Detective Agency bustled with life. Kunikida barked orders and typed furiously. Clerks ran and dodged each other, delivering papers and writing down information.

Dazai was sprawled out on the couch in the section for clients. His headphones were playing music, cancelling out the cacophony around him.

Ranpo sat down on the other couch. He was slowly eating potato chips, eyes lazily focused on his coworker. He waited until Dazai opened a questioning eye and tugged his headphones off an ear. "You used the Book," he blandly accused.

Dazai smiled. "Yes, I did," he easily admitted. "I don't have it anymore."

Ranpo loudly bit a chip in half, mildly impatient. He narrowed his eyes. "Do you know where it is?"

Dazai hummed, tilting his head thoughtfully. He shrugged. "No, not now." Ranpo didn't need to know, so Dazai wouldn't tell him. The less people who knew, the better. Plus, it was none of Ranpo's business, nor was it Dazai's secret to give out.

No one uninvolved heard their conversation. Everything else going on was far too loud.

XXX

Yokohama

Chuuya's apartment

Physical age 25

Mental age 35

Chuuya sat on his couch. He reached out with his senses. He grasped the string firmly in his hand, he wrapped it around his hand, and pulled.

The Book knew how to bend reality-time and space. Chuuya was the new Book, albeit one with a less bland personality and more physically able body.

The Book could not make wishes. It could not change anything by itself. It waited, bored, for someone to come along and request something. But Chuuya was a person as well, not exactly human, never human; but a person, a being distinct from the Book and its powers. This led to the first loophole Chuuya exploited. Because he fulfilled both of the conditions for changing things, as he was the Book and he was not the Book, somehow.

Chuuya made a wish. He changed one thing, not much. But by doing that, he changed many things-things that were, things that are, and things that would be.

The second loophole was how karma was counted and how appropriate punishment was chosen to balance accounts-because it didn't count the butterfly effect as Chuuya had learned a while ago. No, the Book did not count the ripple effect, only the thing you changed directly. If your wish was to tip over a glass of water, the Book wouldn't punish you for changing where the water in the glass was, only tipping over the cup.

His karma was small enough that he just got a deep, painful cut on his inner thigh. Inscribed were words in a language different than Japanese. He could read them, somehow.

The change was small, often the most earth shaking changes are. It was about a cat-a calico cat, orange, brown, and white. He used to frequent a bar called Lupin, and was never really a cat at all, although he appeared as one.

The change was for the cat-yet he was not a cat-to always be in the right place at the right time. It was small, but it was the perfect change for things to end up the best way.

It was small; but that...

One...

Small...

Wish...

Changed...

Everything.

No one would ever get their hands on the Book.

Yokohama would never burn again.

Chuuya would make sure of it.

A/N

The Time Machine is written in second person, addressing the reader as You. You are a guest at the time traveler's party, hearing his stories of traveling through time. Because of the tense being second person, I decided that H. G. Wells cannot use the time machine, only other people can.

You can experience personality changes after a concussion. Hence why Chuuya gave himself one to explain away acting differently.

As for the title, Knock-on effect is the secondary, often unintended result of doing something. This is less a reference to the butterfly effect, and more foreshadowing that something will go wrong in a general sense. Like… say, gaining the powers of a reality-changing object by accident.

I wanted to write a time traveler Chuuya and a Book!Chuuya fic, so I lumped them together. It worked out pretty well.

-Silver


End file.
